问题 单项选择题

调和模型石膏时,调拌速度过快,将导致

A.强度增加,膨胀减少

B.强度降低,膨胀增加

C.强度增加,膨胀增加

D.强度降低,膨胀减少

E.硬度增大,强度增加

答案

参考答案:B

解析: 模型石膏的固化是半水石膏向二水石膏晶体转变的过程。调和速度过快,则会产生过多的结晶中心,使晶体的生长相互挤压,产生膨胀;同时由于晶核数多,晶体细小,材料的强度也相应降低;另外过快的调拌还会带进气泡降低强度。

阅读理解

The sun went down when an old man came to a small mountain village with a heavy bag. He found an inn(小旅馆) and wanted to stay there for the night.

After he had gone to his room, the owner of the inn said to his wife, “Look at his heavy bag, dear! I’m sure there’re a lot of valuable(贵重的) things. I want to steal it when he’s asleep tonight.” “No, no,” said his wife. “He must look for his bag tomorrow morning. Then he’ll take you to the police station.”

They thought hard and at last the woman had an idea. “We have forgetful grass,” said the woman. “Why not put some into his food? If he has the food, he’ll forget to take his bag away tomorrow morning.” “How clever you are!” said the owner, “don’t forget it when you cook supper for him.”

The old man had the food with forgetful grass and went to bed. The next morning, when the owner got up, he found the door was open and the old man had left. He looked for the bag for a long time, but he didn’t find it. He hurried to wake his wife up and said angrily, “What a fool! Your forgetful grass isn’t useful at all!”

“No, no,” said the woman. “I don’t think so. He must forget something.”

“Oh, I’ve remembered!” the owner called out suddenly, “He forgot to pay us the bill!”

1. The old man carried __________ when he got into the inn.

A. a large camera                   B. a heavy bag

C. an umbrella                    D. a heavy basket

2. What did the owner want to do?  _________________

A. He wanted to call the police.        

B. He wanted to kill the old man.

C. He wanted to steal the old man’s bag.

D. He wanted to invite the old man to dinner.

3. The old woman put _____________ into the old man’s food.

A. some sleeping pills           B. some pepper

C. some beef                 D. forgetful grass

4. The next morning the owner found ____________.

A. the old man left his bag in the inn   B. the bag was still there

C. the old man had died         D. the old man had gone with his bag

5. The old man forgot to __________________.

A. pay the owner the bill                B. take his bag

C. look at the time                   D. say goodbye to the owner

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